To celebrate the 20th anniversary of the Diablo franchise, Blizzard has released a series of in-game events and digital goodies across each of its games — Heroes of the Storm, Overwatch, Hearthstone, StarCraft II, World of Warcraft, and, naturally, Diablo III. Most of the celebration features cosmetic items for each title that are automatically added to your inventory or unlocked by playing a few matches, but Diablo II, Hearthstone, and World of Warcraft are host to specific events that you can participate in. World of Warcraft’s anniversary event is a bit difficult to access. Here’s everything you need to know about accessing it and claiming your achievement before it ends.
For the Diablo anniversary event, Blizzard has basically recreated the [infamous Secret Cow Level from Diablo II](http://diablo.gamepedia.com/SecretCow_Level(Diablo_II) within World of Warcraft. Located in a phased instance of Duskwood, the Secret Cow Realm is a small farmstead completely covered in cows led by a rare elite mob called the Cow King, who you’ll have to eliminate to claim your rewards and achievement.
Getting to the Secret Cow Realm requires you to find a Treasure Goblin. These little guys are scattered across the Broken Isles and can be found in a few different locations, however, we found the most effective way was to complete a heroic dungeon with LFG or some friends as there’s guaranteed Treasure Goblin spawn once you down the final boss of the dungeon. If killed before casting Escape Portal, the Treasure Goblin will open a yellow portal that grants you entrance into the Secret Cow Realm. These guys also have a chance of dropping the Horadric Satchel, which is a unique 28-slot bag exclusively available through the anniversary event.
Once inside, you’ll find yourself in a special version of the Yorgen Farmstead in Duskwood. Dying in the Secret Cow Level at any point will teleport you out of it and require you to kill another Treasure Goblin to access it again, so be especially careful if you’re on a PvP realm or flagged for PvP combat. When you exit the portal, head outside and look for a stable-like building on your left. Here’s where you’ll find the Cow King, who you must kill to claim your loot. After you’ve looted him, you’re safe to head back outside of the Secret Cow Level and play your new Twelve-String Guitar to earn the anniversary achievement on your account.
You’ll probably notice a few other items in your inventory you received from the Treasure Goblins or the Cow King like a Blank Diabolic Tome and a few Scrolls of Town Portal. These items are required to piece together the second major reward from the event, the Tome of Town Portal, which functions like a second hearthstone. Collect a total of 10 of these scrolls, and then combine them with the Black Diabolic Tome to claim it as your own.